This post raises some interesting questions about information assurance in general.

Hard disks, being electromechanical devices will fail - the only unknown is when, and if you are worrying about data integrity and confidentiality after the failure - its too late, so if the data is valuable enough to consider using the services of a data recovery comp[any, you should be backing it up - regularly.

Secondly, if the data is so sensitive that you wouldn't want a data recovery service to see it, you should consider protecting it with some form of encryption, but in any event, if the disk does fail, it should still be rendered useless by physical destruction - you can then restore from the backup. of course, the back up also needs to be protected, either by physically securing it, and/or applying encryption to it.

The methods of encryption will depend on what level of inconvenience you can live with and the circumstance, and could range from single file encrypttion, or on-the-fly disk encryption.